In a small bowl, mash to combine butter, thyme, garlic and zest with a pinch of salt and pepper. Transfer the butter onto parchment paper or plastic wrap. Roll into a log and chill for 2 hours.
Pat steaks dry with paper towels and season liberally all over kosher salt and freshly cracked black pepper. In a large cast-iron skillet, heat 1 Tbsp canola oil over high heat until shimmering. Cook the steaks one at a time turning every 1-2 minutes until brown and crusty, about 4 minutes in total.
Reduce heat to medium and add the 2 Tbsp of the butter mixture. Tilt the skillet toward you and spoon the foaming butter over the steak repeatedly. Continue flipping and basting until an instant-read thermometer inserted into the thickest part registers 125°F for medium-rare, about 8 to 10 minutes more. Repeat with the other steak.
Transfer the steaks to a cutting board and rest for 10 minutes. Cut the steaks off the bone, then slice across the grain and serve.